8 fish dead in less than one day

OP, here is a veterinary source on columaris.

This would be the most trustworthy source for information regarding it.

Some notes from that:

Regarding the pale patch:


View attachment 349317

And yes, acute cases of this disease can kill asymptomatically!
View attachment 349318

It's not restricted to dirty tanks, it is present in number in anyone's tanks and often strikes when a fish is compromised due to a stresser (moving tanks, a new environment, change of parameters, chronic disease, shipping, etc)
Thank you for the info. I have seen the SAE going after some of the fish that aren't moving as much today. Some on the back. Would it harm any of the fish to treat with Kanaplex if they do not have a bacterial disease?
 
Have you only got the AquaClear filter on the tank?
How often and how do you clean the filter?
What sort of filter materials/ media do you have in the filter?

What did you feed the fish yesterday and today?
Have they had anything different in their diet?
If you use frozen food, is it frozen when you get it home, and is your freezer working properly?

How old is the dry food you feed them?
Does it look ok and feel dry?
Dry food can absorb moisture form the air and go mouldy and this can kill fish. Try to use dry food within one month of opening it and if possible, within 2 weeks of opening it. If you have a lot of dry food, freeze most of it and only keep a small amount out for the fish.

Has anything new been added to the aquarium in the last few weeks?

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I doubt this is Columnaris. None of the fish have symptoms except the Melanotaenia lacustris rainbowfish and that looks more like a physical wound or an external protozoan infection like Costia, which won't respond to antibiotics.

The white on the tip of the dorsal fin of the lacustris rainbow is excess mucous and the damaged area also has excess mucous on it.

I would not be adding medications at this stage because diseases like Columnaris and Costia don't wipe out a bunch of healthy fish in one day and leave no external symptoms except on one fish. And both of these diseases occur in dirty tanks and this tank gets a 50% water change every 14 days (last water changes was 10 days ago), which should be sufficient to keep it clean.

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Regarding the stringy white poop. I wouldn't worry too much about that yet. The most important thing is to stop the fish dying and then you can deal with this after, assuming they live.

Stringy white poop can be caused by an internal bacterial or protozoan infection, or intestinal worms. There is more information about the causes and treatments in the link below.

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If your aquarium doesn't have a cover on it, then the cat might have contaminated the water.

Has the cat been treated with anything (external flea or worm treatment, medicated shampoo, etc) in the last few weeks?

Has the house or property been sprayed for anything in the last 12 months?
A lot of pesticides are lethal to aquatic organisms and last for years. If the cat has come in contact with these chemicals, and put its paw or tail in the water, it might be enough to wipe out the fish.

At this stage I would be trying big daily water changes and try to clean the sand with a gravel cleaner. Maybe add some carbon to the filter and then hope for the best.
Thank you for the link
 
Thank you for the info. I have seen the SAE going after some of the fish that aren't moving as much today. Some on the back. Would it harm any of the fish to treat with Kanaplex if they do not have a bacterial disease?
It's not ideal to treat blindly, but there's enough red flags here for it imo that it should be warranted.

However, your cycle will take a hit, to be warned.


You can attempt a salt treatment for columnaris as a trial and see if it helps. I'm sure the salt man Colin can advise on your salt dosing
 
I still think it's poisoning of some sort but not sure what has gotten in there. If you want to try salt, the directions are below.

SALT
You can add rock salt (often sold as aquarium salt), swimming pool salt, or any non iodised salt (sodium chloride) to the aquarium at the dose rate of 1 heaped tablespoon per 20 litres (5 gallons) of water. If there is no improvement after 48 hours you can double that dose rate so there is 2 heaped tablespoons of salt per 20 litres.

If you only have livebearers (guppies, platies, swordtails, mollies), goldfish or rainbowfish in the tank you can double that dose rate, so you would add 2 heaped tablespoons per 20 litres and if there is no improvement after 48 hours, then increase it so there is a total of 4 heaped tablespoons of salt per 20 litres.

Keep the salt level like this for at least 2 weeks but no longer than 4 weeks otherwise kidney damage can occur. Kidney damage is more likely to occur in fish from soft water (tetras, Corydoras, angelfish, Bettas & gouramis, loaches) that are exposed to high levels of salt for an extended period of time, and is not an issue with livebearers, rainbowfish or other salt tolerant species.

The salt will not affect the beneficial filter bacteria but the higher dose rate (4 heaped tablespoons per 20 litres) will affect some plants and some snails. The lower dose rate (1-2 heaped tablespoons per 20 litres) will not affect fish, plants, shrimp or snails.

After you use salt and the fish have recovered, you do a 10% water change each day for a week using only fresh water that has been dechlorinated. Then do a 20% water change each day for a week. Then you can do bigger water changes after that. This dilutes the salt out of the tank slowly so it doesn't harm the fish.

If you do water changes while using salt, you need to treat the new water with salt before adding it to the tank. This will keep the salt level stable in the tank and minimise stress on the fish.

When you first add salt, add the salt to a small bucket of tank water and dissolve the salt. Then slowly pour the salt water into the tank near the filter outlet. Add the salt over a couple of minutes.
 
I still think it's poisoning of some sort but not sure what has gotten in there. If you want to try salt, the directions are below.

SALT
You can add rock salt (often sold as aquarium salt), swimming pool salt, or any non iodised salt (sodium chloride) to the aquarium at the dose rate of 1 heaped tablespoon per 20 litres (5 gallons) of water. If there is no improvement after 48 hours you can double that dose rate so there is 2 heaped tablespoons of salt per 20 litres.

If you only have livebearers (guppies, platies, swordtails, mollies), goldfish or rainbowfish in the tank you can double that dose rate, so you would add 2 heaped tablespoons per 20 litres and if there is no improvement after 48 hours, then increase it so there is a total of 4 heaped tablespoons of salt per 20 litres.

Keep the salt level like this for at least 2 weeks but no longer than 4 weeks otherwise kidney damage can occur. Kidney damage is more likely to occur in fish from soft water (tetras, Corydoras, angelfish, Bettas & gouramis, loaches) that are exposed to high levels of salt for an extended period of time, and is not an issue with livebearers, rainbowfish or other salt tolerant species.

The salt will not affect the beneficial filter bacteria but the higher dose rate (4 heaped tablespoons per 20 litres) will affect some plants and some snails. The lower dose rate (1-2 heaped tablespoons per 20 litres) will not affect fish, plants, shrimp or snails.

After you use salt and the fish have recovered, you do a 10% water change each day for a week using only fresh water that has been dechlorinated. Then do a 20% water change each day for a week. Then you can do bigger water changes after that. This dilutes the salt out of the tank slowly so it doesn't harm the fish.

If you do water changes while using salt, you need to treat the new water with salt before adding it to the tank. This will keep the salt level stable in the tank and minimise stress on the fish.

When you first add salt, add the salt to a small bucket of tank water and dissolve the salt. Then slowly pour the salt water into the tank near the filter outlet. Add the salt over a couple of minutes.
I think you are probably right about the poisoning. I'm not sure from what though. After the 75% water change, I haven't had any more deaths. 4 of the fish do not act normal, but of those, 3 seem to be getting a little better. Will the salt mainly help if the problem isn't poisoning?
 
Salt will help if it's an external protozoan infection like Costia, Chilodonella or Trichodina.

Salt can help if it's the start of a Columnaris infection but generally won't completely stop the infection in that particular fish. The salt slows the spread of the infection in the individual fish and between the different fish in the tank, and buys you time to get antibiotics.

I would do another big water change today and see how they look tomorrow. If you add salt or any medication now, it could kill the fish due to their weakened state. If you can wait 24 hours and see how they look tomorrow, that at least gives the fish 24 hours without anything new in the water and if they are still dying, then you can add something. But generally with poisoning, you want the animal exposed to as little stuff as possible after the poisoning so the liver can help remove the toxins from the body. The less stuff they are exposed to, the less stress on the liver, and the faster they can recover.
 
It's not ideal to treat blindly, but there's enough red flags here for it imo that it should be warranted.

However, your cycle will take a hit, to be warned.


You can attempt a salt treatment for columnaris as a trial and see if it helps. I'm sure the salt man Colin can advise on your salt dosing
Seachem states that Kanaplex will not impact an established cycled filter. That has been my experience as well.
 
My cat sometimes gets on the tank (tried everything to keep her off). Maybe she could have gotten something into the tank??
Do you use any type of flea and tick preventative on your cat? Is the litter you use scented? Do you use any type of no rinse cleaning wipes on your cat? All of these things could, potentially, have toxins that would impact the fish, though I think that the first one (flea nd tick) would be the most impactful.
Now, here is another crazy thought, and believe me, this is coming from someone who has cats, and has had cats my whole life - is there a chance that your cat peed in the tank? I have had several cats over the years, that when they perceived that "something" was important to me and was getting more attention than they were, well... cats can be naughty 😾
 
Salt will help if it's an external protozoan infection like Costia, Chilodonella or Trichodina.

Salt can help if it's the start of a Columnaris infection but generally won't completely stop the infection in that particular fish. The salt slows the spread of the infection in the individual fish and between the different fish in the tank, and buys you time to get antibiotics.

I would do another big water change today and see how they look tomorrow. If you add salt or any medication now, it could kill the fish due to their weakened state. If you can wait 24 hours and see how they look tomorrow, that at least gives the fish 24 hours without anything new in the water and if they are still dying, then you can add something. But generally with poisoning, you want the animal exposed to as little stuff as possible after the poisoning so the liver can help remove the toxins from the body. The less stuff they are exposed to, the less stress on the liver, and the faster they can recover.

Do you use any type of flea and tick preventative on your cat? Is the litter you use scented? Do you use any type of no rinse cleaning wipes on your cat? All of these things could, potentially, have toxins that would impact the fish, though I think that the first one (flea nd tick) would be the most impactful.
Now, here is another crazy thought, and believe me, this is coming from someone who has cats, and has had cats my whole life - is there a chance that your cat peed in the tank? I have had several cats over the years, that when they perceived that "something" was important to me and was getting more attention than they were, well... cats can be naughty 😾
No flea or tick treatment. Litter is corn based unscented. It does have some kind of enzymes in it I think. I hope she didn't pee in it! She can be rotten though! I checked ammonia level and it was 0. Even with beneficial bacteria I would think ammonia would be high. Maybe? I am going to put a barrier over the waterfall area of the AquaClear filter though to keep her from being able to touch the water just in case. Thank you!
 
I still think it's poisoning of some sort but not sure what has gotten in there. If you want to try salt, the directions are below.

SALT
You can add rock salt (often sold as aquarium salt), swimming pool salt, or any non iodised salt (sodium chloride) to the aquarium at the dose rate of 1 heaped tablespoon per 20 litres (5 gallons) of water. If there is no improvement after 48 hours you can double that dose rate so there is 2 heaped tablespoons of salt per 20 litres.

If you only have livebearers (guppies, platies, swordtails, mollies), goldfish or rainbowfish in the tank you can double that dose rate, so you would add 2 heaped tablespoons per 20 litres and if there is no improvement after 48 hours, then increase it so there is a total of 4 heaped tablespoons of salt per 20 litres.

Keep the salt level like this for at least 2 weeks but no longer than 4 weeks otherwise kidney damage can occur. Kidney damage is more likely to occur in fish from soft water (tetras, Corydoras, angelfish, Bettas & gouramis, loaches) that are exposed to high levels of salt for an extended period of time, and is not an issue with livebearers, rainbowfish or other salt tolerant species.

The salt will not affect the beneficial filter bacteria but the higher dose rate (4 heaped tablespoons per 20 litres) will affect some plants and some snails. The lower dose rate (1-2 heaped tablespoons per 20 litres) will not affect fish, plants, shrimp or snails.

After you use salt and the fish have recovered, you do a 10% water change each day for a week using only fresh water that has been dechlorinated. Then do a 20% water change each day for a week. Then you can do bigger water changes after that. This dilutes the salt out of the tank slowly so it doesn't harm the fish.

If you do water changes while using salt, you need to treat the new water with salt before adding it to the tank. This will keep the salt level stable in the tank and minimise stress on the fish.

When you first add salt, add the salt to a small bucket of tank water and dissolve the salt. Then slowly pour the salt water into the tank near the filter outlet. Add the salt over a couple of minutes.
I have had a total of 23 fish die from yesterday morning when I noticed 3 dead until around noon today. Since then, and my second big water change, no new deaths. Of the 15 fish I have left, 3 are not eating, hanging out near the top of the tank and coloring isn't great. One was having trouble keeping itself upright, but is better with that now. The rest are eating and acting and looking pretty normal. Should I try salt, or leave things alone?
 
I have had a total of 23 fish die from yesterday morning when I noticed 3 dead until around noon today. Since then, and my second big water change, no new deaths. Of the 15 fish I have left, 3 are not eating, hanging out near the top of the tank and coloring isn't great. One was having trouble keeping itself upright, but is better with that now. The rest are eating and acting and looking pretty normal. Should I try salt, or leave things alone?
Some of the more normal ones are occasionally breathing (mouth open and closing) a little fast.
 
I have had a total of 23 fish die from yesterday morning when I noticed 3 dead until around noon today. Since then, and my second big water change, no new deaths. Of the 15 fish I have left, 3 are not eating, hanging out near the top of the tank and coloring isn't great. One was having trouble keeping itself upright, but is better with that now. The rest are eating and acting and looking pretty normal. Should I try salt, or leave things alone?
I would probably leave the salt out for another day and do another water change. The 3 that are hanging out by the surface might not make it and salt probably won't help them. If more start breathing rapidly, then add salt after you do the water change.

Cats don't pee in water so your cat didn't do that.
 
I would probably leave the salt out for another day and do another water change. The 3 that are hanging out by the surface might not make it and salt probably won't help them. If more start breathing rapidly, then add salt after you do the water change.

Cats don't pee in water so your cat didn't do that.
Thank you!
 
I would probably leave the salt out for another day and do another water change. The 3 that are hanging out by the surface might not make it and salt probably won't help them. If more start breathing rapidly, then add salt after you do the water change.

Cats don't pee in water so your cat didn't do that.
Thank you!
 

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